A playback apparatus has been proposed, which is designed to playback a content that is composed of a plurality of components selected from moving picture data, image data, audio data and text data. If provided as a portable apparatus, the playback apparatus can playback contents in various environments. In some environments, however, the user cannot enjoy listening to any audio content or viewing any video content.
Although the user wants to manage the read/unread state of each component of the content, he or she cannot listen to any sound included in the content or view an image included in the content, depending on the environment in which the apparatus is used. It is inevitably difficult to manage the read/unread state of each component.